The method.
Each part of the protocol was chosen for one purpose: to make a small change in one brain readable, with a known margin of error.
The protocol.
| Site | HELIMED Katowice, Ceglana 7 |
|---|---|
| Scanner | Siemens MAGNETOM Lumina 3T, one unit, software version locked |
| Sequence | MP2RAGE, 1 mm isotropic |
| Scans per visit | Two MP2RAGE scans, without leaving the table |
| Calibration | B1 map, every visit |
| Your preparation | Morning visit, same preparation every time |
| Interval | One visit a year |
| Scans from elsewhere | Not accepted |
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Why each part is there.
MP2RAGE
The sequence records two images at different inversion times in one acquisition and combines them, cancelling the brightness variation that comes from the receive coil and leaving contrast that depends mainly on tissue T1, so tissue boundaries are drawn more consistently from scan to scan.
Two scans, without leaving the table
Taking both scans in one session and one position means the only difference between them is the measurement itself, which gives a direct estimate of your noise on the day.
B1 map
The B1 map records how the scanner’s radio-frequency field varies across your head, so its remaining effect on MP2RAGE contrast can be corrected at every visit.
Your preparation
The protocol covers you as well as the scanner: visits take place in the morning and follow the same preparation each time, because hydration and time of day shift measured brain volume slightly.
A centre built for the person in the scanner.
Scans take place at HELIMED’s new Ceglana centre in Katowice, designed around the experience of the person being scanned.
Measured against your own scans.
Each new scan is aligned with your earlier ones, and change is measured directly between them, in your own anatomy.
How the margin of error is computed.
The smallest detectable change is the amount a result has to move before we call it a change. It is built on the noise measured for each person at every visit.
Scan-rescan study
Published here once the study is complete.